The invention relates, in general, to an apparatus and method for acquiring data from bar codes. In particular, this invention relates to a system for re-creating the contents of a bar code label resulting from partial scans produced by different axis of a scanning beam.
Prior art in the form of patent U.S. Pat. No. 4,289,957 has attempted to read bar codes such as UPC codes through a technique using partial scans. However, the teaching of this patent is very limited in scope and in its overall capability. One such limiting factor is that the patent teaches that the scanning pattern must be divided into a top and bottom sweep thereby generating an upper half message and a lower half message; therefore, if the bar code requires that fourteen characters be read and interpreted, the top and bottom sweeps must respectively produce seven characters each to generate a completed fourteen character signal prior to decoding. If a sweep produces less than seven characters, no decoding can be produced; hence, an incomplete message is generated and the scan cycle must be repeated. This procedure is not conductive to a need for high speed bar code technology.
The above shortcoming may be further delineated. The prior art requires that the top and bottom sweeps are consecutive and always begin with a start or security code followed by seven utility characters. If such a security code is not found during a sweep, the information acquired cannot be utilized. In other words, the prior art patent teaches that the characters of a scanned code must be sequentially read from the first character to the last character of a set of seven characters including the security code or the data received cannot be interpreted; and, the last seven characters must also be read in sequence to complete the data capture. This is deemed to be too restrictive and time consuming for modern day decoding of a product code data field where more than one-half of the data is captured by a scanning beam.
The present invention is designed to produce a new bar code read and decoding method that is initiated by a sweep action of the laser beam as it impinges upon the bars and spaces of the coded symbol; furthermore, even though the beam sweep results in only a partial read of information, it is placed in a buffer memory until the remainder of the code is read in some following random scan. In this invention, the beam is omni-dimensional which produces a multi-axis scan. As a result, the present invention is designed to capture coded data with a random scanning action which enables the system to be more versatile. Furthermore, the present invention is designed to capture complete information on a coded label via partial scans of information even though the scans are initiated against the last character first.
It has been observed, in the present state of the art, that manufacturers in their efforts to add more information to existing codes such as the UPC (Universal Product Code), Code 39, Code 128, and Interleaved 2/5 (industrial codes) have done so with the concomitant effect that the code's aspect ratio (i.e., height of a bar/overall length of code) has decreased. As a result of the lowering of the aspect ratio, it has become more difficult for the art to achieve a high success rate in achieving initial reads of manufacturer's discount coupon and particularly when it has been clipped from a newspaper. This is particularly the case when coded coupons are placed upon a conveyor belt that is traveling at a speed of two hundred and fifty feet per minute at the manufacturer's redemption center. It is this procedure that is presently being utilized by the coupon issuers to ascertain the number of the coupons that have been redeemed by purchasers.
The scanning art, as represented by the above cited patent cannot achieve, it is believed, a reading of product codes with small aspect ratios on the order of 0.25:1 unless the label is in perfect alignment with two successive scan patterns. However, in actual practice the label is often skewed to the scan axis in its direction of travel and the bar code must be captured by a plurality of scans which may not necessarily be successive.
It is accordingly an object of this invention to provide a new and improved apparatus and method for reading bar codes that allows information to be captured using random sweeps of a scanning beam.